The present invention relates to power-branched gears, including two planet gears, one per branch.
Power branching in speed reduction gearing is known to include two planet gears, a common drive shaft, and a common driven shaft. The power and torque to be transmitted between these two shafts is branched in order to reduce the size of the gears involved. The German printed patent application No. 26 18 882 describes an example for such a gear. The two branches are recombined in that both planet gear carriers are connected to the output shaft. This publication, moreover, describes a particular way to compensate or balance any torsional load differences in the two branches. It suggests providing the two planet gears with oppositely oriented helical teeth. Moreover, the two planet gear carriers (Spiders) are interconnected as well as connected to the output shaft by means of dualarticulated joint or universal couplings. Radial loads are balanced as between the two branches by means of the radial mobility of the input shaft which carries the two sun gears. Radial load balance and torsional load balance are, thus, mutually dependent upon each other. This operational condition brings forth considerable requirements with regard to the accuracy of the teeth; in particular, if the balancing is also to be obtained upon reversing the direction of rotation! Moreover, helical teeth are required in this system which produces axial forces, and these have to be taken up separately.